I don’t think this is the parse you want. Note how there is an unknown rel, which the ERG introduces to allow fragments (e.g. try parsing “the dog”, or “the dog?”). The free_relative_q is for a construction like “what we saw surprised us”. So this parse means something like “the things which are you and which are holding something?” (a noun phrase being used as a question).

If you really do want this parse, the suspicious bit is h15, which should either be identified with h8 or connected via another rel such as subord.

I’m trying to make sure my “MRS Solver” can create all valid fully scoped trees from any proper MRS structure so even if I wouldn’t use this in my game I want to make sure I don’t have a bug in my solver.

When you say "h15 , which should either be identified with h8" do you mean that the ACE parser should have given them both the same handle? I.e. it is a bug? Or is there some operation I need to do in addition to assigning handles to holes in this case?

Same question for “or connected via another rel such as ‘subord’” I’m not sure what you meant by that one. I thought the only thing that needed to be done to completely resolve an MRS structure was assigning handles to holes (while maintaining constraints and scope of variables). Are there more steps that need to be done sometimes?

Re: Well-formed: I was trying to use the Copestake et al (2005) definition (maybe improperly): “A well-formed MRS structure is an MRS structure that link-subsumes one or more scope-resolved MRS” which I thought meant that there was no underspecification left…

Re: Well-formed: I was trying to use the Copestake et al (2005) definition (maybe improperly): “A well-formed MRS structure is an MRS structure that link-subsumes one or more scope-resolved MRS” which I thought meant that there was no underspecification left…

No, “link-subsumes” means that it is a possibly underspecified form that can become a scope resolved form by adding (not removing or replacing) links (or label equalities). You can imagine an MRS that can’t possibly become a valid scope-resolved form without removing some improper constraint, or perhaps the DAG is disconnected, etc. These would be ill-formed.

From section 4.1 in Copestake et al. 2005 (p294 in the PDF I’m looking at, but it’s the 14th page of the PDF):

In order to formalize the idea that an underspecified MRS will correspond to a set of (potentially) more than one object-language expression, we will define the relationship of an arbitary MRS structure to a set of scope-resolved MRSs. The intuition is that the pieces of the tree in an underspecified MRS structure may be linked up in a variety of ways to produce a set of maximally linked structures, where a maximally linked structure is a scope-resolved MRS. Linking simply consists of adding equalities between handles. Linking can be regarded as a form of specialization, and it is always monotonic. So if we have an MRS M that is equivalent to an MRS M′ with the exception that M′ contains zero or more additional equalities between handles, we can say that Mlink-subsumesM′. If M ≠ M′ we can say that M strictly link-subsumes M′.

I’m trying to make sure my “MRS Solver” can create all valid fully scoped trees from any proper MRS structure so even if I wouldn’t use this in my game I want to make sure I don’t have a bug in my solver.

Remember this discussion? Resolving scope is a smaller problem than coming up with precise logical interpretations, but there’s a general point that not all of the ERG’s MRSs are of equally good quality. For well-understood constructions, you will get a good MRS; for difficult constructions, you will get a reasonable placeholder MRS that is logically questionable but good enough for many applications (e.g. modified quantifiers, like in “almost everyone left”); and in some cases, there are bugs in the grammar.

guyemerson:

If you really do want this parse, the suspicious bit is h15, which should either be identified with h8 or connected via another rel such as subord.

By this, I meant that the MRS is suspicious and it looked to me like a bug in the ERG, which is why I asked for the version. (Bug reports can be made here: https://github.com/delph-in/erg .) It seems that v2018 has more parses than v1214. There are four readings with an unknown and free_relative_q, of which one has a subord, two have a nominalization, and the last one is the one you’ve posted about. It might be that this is a bug, or it might be that this is needed as a robust parse for some other kind of fragment.

Thanks. I thought my example was minimal…I guess I don’t understand what minimal means in the case of the ERG. I assumed it meant “small sentence that doesn’t generate a huge complex MRS”. Is there something else I should shoot for?

Maybe “minimal” isn’t quite the right word. Certainly, “small sentence that doesn’t generate a huge complex MRS” is a good place to start. The trouble with this reading of this sentence is that it’s a fragment and quite weird, semantically, so it’s not immediately clear what’s going wrong (e.g. is being a fragment relevant? Or the copula? Or the pronoun? Or the question?).

@guyemerson in what sense is what are you holding a fragment?
Though I agree trying to find a similar sentence with the mismatch without as many of the question, pronoun, or auxiliary (not copula) phenomena would be good. Or at least trying to remove one and see if the problem still exists.

It’s a fragment for the intended reading (see MRS in first post), in which “what are you” is a free relative clause (so “are” is a copula, not an auxiliary), and “holding” is a modifier. The obvious reading has no problems with its MRS. In the GitHub issue, I have given another sentence illustrating the same problem but where the intended reading is clearer.

Thanks for the bug report. There is indeed a bug in the grammar (both in the 2018 version and until now also in trunk), which Guy rightly notes has to do with a missing identity in the hook of the free relative phrase that the (reduced) relative construction modifies. More specifically, the construction for free relative clauses (hd-cl_fr-rel_c) fails to identify its LTOP with that of its free-relative pronoun daughter. I’ll document the fix on Github where it belongs once I have tested it.

So your understanding, Eric, is sound here: there should normally be the same number of holes and labels to fill them, so report a mismatch like this as a bug, I note BTW that in the upcoming next release (2020) of the ERG, the grammar no longer produces that counterintuitive analysis for your original example, since the free relative “what” does not actually like agreeing with a following plural VP (no wonder you had a hard time envisioning the motive for that analysis). But the bug remained in Guy’s variant “whoever sleeps barking naps”, so needed to be fixed in any case.

@Dan, great. Thanks for the fix! I’ve been able to work around it by changing my MRS solver to get ignore any parses that have a hole/label count mismatch, but I’ll have it spit them out so I can report them to you guys.